When a user on Facebook "likes" another users comment left on a status without donating their two cents in the actual conversation at hand.

Reasons for this maybe because:

(1) have nothing to contribute to the status.
(2) don't want to receive useless notifications by liking/commenting the actual status or
(3) it was that damn good of a comment and worthy of receiving props.

Chervony: "Molly keeps Ghost Liking the comments I leave on Diaz' status'! It's like she's here with us listening to our every word!"